Yatsugatake South Base Observatory (八ヶ岳南麓天文台 Yatsugatake Nanroku Tenmondai) is an observatory in Hokuto, Yamanashi, Japan. Its observatory code is 896. It is frequently used due to its closeness to the Greater Tokyo Area, resulting in many asteroid discoveries. Yoshio Kushida has worked on observational research on pre-earthquake natural phenomena.